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Proceedings of the National Academy of Sciences of the United States of America

Description:

PNAS is the world's most-cited multidisciplinary scientific serial.
It publishes high-impact research reports, commentaries, perspectives, reviews,
colloquium papers, and actions of the Academy. In accordance with the guiding
principles established by George Ellery Hale in 1914, PNAS publishes
brief first announcements of Academy Members' and Foreign Associates' more
important contributions to research and of work that appears to a Member to
be of particular importance.

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Terms Related to the Moving Wall

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Complete: Journals that are no longer published or that have been
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Abstract

The lipid binding properties of the membrane protein cytochrome b5 (detergent-extracted from calf liver microsomal preparations) were characterized by studying the interaction of spin-labeled lipids (5-, 12-, and 16-doxylstearic acid and 5- and 16-doxylphosphatidyl-choline, where doxyl refers to the nitroxide moiety) with cytochrome b5, using electron spin resonance spectroscopy. The intact cytochrome b5 molecule immobilizes all of the lipid spin labels, while the segment of cytochrome b5 released by trypsin does not affect lipid mobility. The immobilization of lipid spin labels on the hydrophobic surface of intact cytochrome b5 is not appreciably altered by associating the protein with liposomes. Differences in polarity of the lipid binding sites between cytochrome b5 and phospholipid vesicles were also observed. The lipid binding sites on cytochrome b5 are hydrophobic by conventional criteria, but are more polar than the interior of fluid phospholipid bilayers.